Hard water can literally be the death of your hydroponically grown vegetables and plants. The calcium, magnesium and sodium-rich water can leave mineral deposits that can stunt the growth of your plants, reduce fruit and vegetable yields and cause mineral differences in other areas. However, softening hard water is not difficult.
Determine if you have hard water by observing your house. If you have mineral deposits such as scale on your shower, kitchen sink or coffee maker, you probably have hard water.
Test your water by dropping liquid soap into a glass of water. If suds are not produced by the fifth drop of liquid soap, you probably have hard water.
Check with your municipal water supplier to determine if you have hard water. If you have a well or are otherwise on private water, you can have your water tested by a your local farmer's cooperative or USDA agriculture extension service. Another source for water testing is a local company that sells water treatment equipment.
Mix 1 tsp. of baking soda with 5 gallons of water to soften the water before using it in your hydroponic solution.